回答編集履歴
1
別コード追加
answer
CHANGED
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@@ -38,4 +38,41 @@
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38
38
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39
39
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ClassA::TxtWriter *ClassA::ms_pTW = nullptr;
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40
40
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size_t ClassA::ms_nInstance = 0;
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41
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```
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42
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43
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---
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44
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45
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[追記]
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46
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スマートポインタで強引に．
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47
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うーん…
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48
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49
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```C++
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50
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class ClassA
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51
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{
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private:
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53
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class TxtWriter{ /*(略)*/ };
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54
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public:
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//ClassA のインスタンス生成手段
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static ClassA Create()
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{
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auto spTW = ms_wpTW.lock();
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60
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if( !spTW )
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61
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{
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spTW = std::make_shared<TxtWriter>();
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63
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ms_wpTW = spTW;
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64
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}
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return ClassA( spTW );
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}
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private:
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69
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//private ctor
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70
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ClassA( std::shared_ptr< TxtWriter > spTW ) : m_spTW(spTW) {}
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71
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//data
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72
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std::shared_ptr< TxtWriter > m_spTW;
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//static
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74
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static std::weak_ptr<TxtWriter> ms_wpTW;
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};
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76
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std::weak_ptr<ClassA::TxtWriter> ClassA::ms_wpTW;
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41
78
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```
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